(Should’ve known I would fall)I’m in it(Steppin' on cracks on the floor)That’s right(And your boys at your door)

Ye should have known from before with other girls that she would be unfaithful (her other man is at the door). Cracks on the floor represents bad luck, in the sense of “Step on a crack, break your mother’s back.” It’s a common game to avoid stepping on cracks when walking on a sidewalk or tile floor. Ye should have seen the bad luck coming, basically.

An alternate reading could be “Stepping on tacks,” and in that case it’d be a reference to a sharp pain that Ye should have foreseen but didn’t, and every time, it’s still the same, sharp stabbing.